This study analyzed burn wound swabs collected from 187 hospitalized patients over 3 years to identify aerobic bacterial pathogens and their antibiotic resistance patterns. The most common isolate was Pseudomonas aeruginosa (49.4% of isolates), followed by Staphylococcus aureus (22.2%) and various Enterobacteriaceae species. P. aeruginosa demonstrated high resistance to many commonly used antibiotics but was most susceptible to piperacillin/tazobactam and imipenem. 59% of S. aureus isolates were methicillin-resistant but all were susceptible to vancomycin and linezolid. The high prevalence of multidrug-resistant bacteria indicates a need for improved infection control and empiric antibiotic strategies tailored to

1. International Journal of Medicine and Medical Sciences ISSN: 2167-0404 Vol. 3 (5), pp. 460-463, July,
2013. Available online at www.internationalscholarsjournals.org © International Scholars Journals
Full length Research Paper
Bacteriological profile and antibiogram of aerobic burn
wound isolates in a tertiary care hospital, Odisha, India
Muktikesh Dash1*, Pooja Misra2, Siddhartha Routaray3
1Department of Microbiology, Maharaja Krishna Chandra Gajapati Medical Collage and Hospital, Berhampur University,
Berhampur, Odisha, India.
2Department of Radiodiagnosis, Maharaja Krishna Chandra Gajapati Medical Collage and Hospital, Berhampur
University, Berhampur, Odisha, India.
3Department of Anesthesia, SCB Medical College and Hospital, Utkal University, Cuttack, Odisha, India.
Accepted 09 July, 2013
Approximately 73 percent of all post-burn deaths are directly or indirectly related to septic processes. The
objective of this retrospective study at a tertiary care hospital, Odisha, India was to isolate aerobic bacterial
pathogens and study its antimicrobial resistant pattern in order to establish empiric antimicrobial strategies
for the early treatment of imminent septic events. During three year period (January 2010 to December
2012), 193 burn wound swabs were collected from 187 hospitalized patients. Isolation and identification of
microorganisms was done using standard procedure and each isolate’s antimicrobial resistant pattern was
determined by Kirby-Bauer disc diffusion technique. From 193 swabs, 171 (88.6%) culture positive swabs
and 176 isolates were obtained. The most common isolate was Pseudomonas aeruginosa (49.4%), followed
by Staphylococcus aureus (22.2%), Klebsiella pneumoniae (13.1%) and Acinetobacter baumannii (4.5%). P.
aeruginosa was least resistant to piperacillin/tazobactam (12.6%) and imipenem (9.2%) and 59 percent
methicillin resistant S. aureus (MRSA) was 100% sensitive to vancomycin and linezolid. High prevalence of
multidrug resistant bacteria in our hospital setting suggest continuous surveillance of burn wound
infections and need for development of strict infection control practices.
Key words: Antimicrobial resistance; burn wound; swabs; aerobic bacteria; Pseudomonas aeruginosa;
Staphylococcus aureus.
INTRODUCTION
Burns are one of the most common and devastating form
of trauma. Burn patients are at risk for infection because
of their destroyed skin barrier, suppressed immune
system compounded by prolonged hospital stay and
invasive therapeutic and diagnostic procedures (Mayhall,
2002). Infection is a major cause of morbidity and
mortality in hospitalized burn patients (Mc Manus et al.,
1994). Approximately 73 percent of all post-burn deaths
have been shown to be directly or indirectly caused by
*Corresponding author E-mail: - mukti_mic@yahoo.co.in
Tel. +91 9861046640, 0680-2292526
septic processes (Tancheva and Hadjiiski, 2005). The
pattern of microbial pathogen differs from hospital to
hospital; the varied bacterial flora of infected wound may
change considerably during the healing period (Kumar et
al., 2001).
Multidrug resistant bacteria have frequently been
reported as the cause of nosocomial outbreaks of
infection in burn units or as colonizers of the wounds of
the burn patients (Karlowsky et al., 2004; Agnihotri et al.,
2004). Similarly, antimicrobial resistant pattern among
most frequently isolated bacterial pathogens such as
Pseudomonas aeruginosa, Staphylococcus aureus and
other Gram-negative bacteria has reached to a
alarmingly high level in different studies conducted within
India (Nagoba et al., 1999, Shahid and Malik 2005 and

2. Dash et al. 460
Table 1. Gender wise distribution of swabs collected from burn patients in a tertiary care
hospital, Odisha, India (n=187).
Gender
Total number of burn wound swabs
No. tested (%) No. of growth positive (%) No. of growth negative (%)
Male 86 77 (89.5) 09 (10.5)
Female 101 88 (87.1) 13 (12.9)
Total 187 (100) 165 (88.2) 22 (11.8)
Rajput et al., 2008). Keeping all these facts in view, the
present study was carried out to determine the aerobic
bacterial burn wound isolates in our hospital setting
and describe their resistance patterns, which would
enable the determination of empiric antimicrobial
strategies for the early treatment of imminent septic
events.
MATERIALS AND METHODS
Study area, population and methodology
A total of 187 patients were admitted to the burn unit of a
tertiary care hospital, Odisha, India during three year
period from January 2010 to December 2012. The
retrospective evaluation of patient’s age, sex, severity of
burn injury and hospital stay was carried out on the basis
of case histories.
Data about pathogens were obtained by microbiological
analysis of swabs taken from burn patients. A total of 193
surface swabs were taken from all 187 burn patients.
Swabs were taken when the wound infection was
clinically diagnosed after admission in the burn unit.
Clinical diagnosis of burn wound infection relied on
regular monitoring of vital signs and inspection of entire
burn wound surface, during each dressing change. Local
signs of burn wound infection with invasion included
conversion of a partial-thickness injury to a full-thickness
wound, rapidly extending cellulitis of healthy tissue
surrounding the injury, rapid eschar separation and tissue
necrosis. Repeated pathogens for the same patient were
not included in the study. Verbal informed consent was
obtained from all patients prior to swab collection. The
study was conducted after due approval from institutional
ethical committee.
Sample collection and processing
Whenever applicable, wound surface swabs were
collected from partial-thickness to full-thickness wound
(from 2° to 4° burn). The infected area was swabbed by
using alginate swabs and then cultured aerobically on 5%
sheep blood agar and MacConkey agar. Isolation and
identification was done according to standard procedure
(Baron and Finglod, 1996). All isolates were tested for
antimicrobial susceptibility testing by the standard Kirby-
Bauer disc diffusion method according to Bauer et al
(Bauer et al., 1966). A suspension of each isolate was
made so that the turbidity was equal to 0.5 McFarland
and then plated onto Muller-Hinton agar plate. The
following standard antibiotic discs were used; ampicillin
(10mcg), carbenicillin (100mcg),
sulphamethoxazole/trimethoprim i.e., co-trimoxazole
(23.75/1.25mcg), ciprofloxacin (5mcg), gentamicin
(10mcg), amikacin (30mcg), tobramycin (10mcg),
cephalothin (30mcg), ceftazidime (30mcg), cefoperazone
(75mcg), cefoperazone/sulbactam (75/30mcg),
piperacillin (100mcg), piperacillin/tazobactam
(100/10mcg), imipenem (10mcg), oxacillin (1mcg),
clindamycin (2mcg), vancomycin (30mcg) and linezolid
(15mcg). All dehydrated media and antibiotic discs were
procured from Himedia Labs., Mumbai, India. The results
were interpreted according to Clinical and Laboratory
Standards Institute (CLSI) guidelines (CLSI, 2009). The
control strains used were Escherichia coli ATCC 25922,
Pseudomonas aeruginosa ATCC 27853, and
Staphylococcus aureus ATCC 25923.
Statistical analysis
The data were analyzed for mean, median and standard
deviation by using GraphPad QuickCalcs statistical
software Inc., 2236 Avenida de la Playa La Jolla, CA
92037 USA.
RESULTS
The mean age of patients was 26.7±15.8 years (median
24, 95% confidence intervals 24.4 to 28.9 and range was
from minimum 2 to maximum 75 years). There were 101
females and 86 males with female to male ratio 1.17:1
[Table 1]. The mean total body surface area (TBSA)
percentage among burn patients was 43.5±23.3 %
(median 36, 95% confidence intervals 36.9 to 50.1 and
range was from minimum 10 to maximum 100
percentage).

3. 461 Int. J. Med.Med.Sci.
Table 2. Isolation of aerobic bacterial pathogens from burn wound swabs in a tertiary care hospital,
Odisha, India (n=176).
Gram reaction Type of isolates No. of isolates Percentage (%)
Gram-negative bacilli Pseudomonas aeruginosa 87 49.4
Enterobacteriaceae* 42 23.9
Acinetobacter baumannii 08 4.5
Gram-positive cocci Staphylococcus aureus 39 22.2
*Enterobacteriaceae included - Klebsiella pneumoniae 23 (13.1%), Escherichia coli 7 (3.9%), Proteus
mirabilis 5 (2.8%), Enterobacter aerogenes 3 (1.7%), Citrobacter freundii 3 (1.7%) and Serratia
marcescens 1 (0.6%)
Table 3. Antimicrobial resistant pattern (%) among bacterial isolates in burn patients.
Antibiotic Concent
ration of
disc
(mcg)
Resistant organism (s)
No. (%) of
Pseudomonas
aeruginosa
(n=87)
No. (%) of
Enterobacteriaceae
(n=42)
No. (%) of S.
aureus (n=39)
No. (%) of
Acinetobacter
baumannii (n=08)
Ampicillin 10 NT 39 (92.9) 27 (69.2) NT
Carbenicillin 100 51 (58.6) 21 (50) NT 05 (62.5)
Piperacillin 100 46 (52.9) 17 (40.5) NT 06 (75)
Piperacillin/tazobactam 100/10 11 (12.6) 04 (9.5) NT 01 (12.5)
Gentamicin 10 59 (67.8) 23 (54.8) 17 (43.6) 07 (87.5)
Amikacin 30 43 (49.4) 09 (21.4) NT 05 (62.5)
Tobramycin 10 48 (56.3) 13 (30.9) NT 06 (75)
Ciprofloxacin 5 53 (60.9) 27 (64.3) 23 (59) 07 (87.5)
Sulphamethoxazole/trim
23.75/1.
NT 29 (69) 26 (66.7) NT
ethoprim
25
Cephalothin 30 NT 33 (78.6) 29 (74.4) NT
Ceftazidime 30 63 (72.4) 26 (61.9) NT 07 (87.5)
Cefoperazone 75 61 (70.1) 18 (42.9) NT 06 (75)
Cefoperazone/sulbacta
75/30 24 (27.6) 07 (16.7) NT 02 (25)
m
Imipenem 10 08 (9.2) 0 NT 0
Oxacillin 1 NT NT 23 (59) NT
Clindamycin 2 NT NT 13 (33.4) NT
Vancomycin 30 NT NT 0 NT
Linezolid 15 NT NT 0 NT
NT- Not tested, mcg- micrograms, Enterobacteriaceae included - Klebsiella pneumoniae -23, Escherichia coli -7, Proteus mirabilis- 5,
Enterobacter aerogenes- 3, Citrobacter freundii -3 and Serratia marcescens- 1 isolates.
A total of 193 surface swabs were taken from burn
wounds, out of which 171 (88.6%) swabs were culture
positive and rest 22 (11.4%) were sterile. From 171
culture positive swabs only 5 swabs yielded more than
one isolate, thus a total of 176 bacterial isolates were
obtained. The most predominant bacterial isolate was
Pseudomonas aeruginosa 87 (49.4%), followed by other
gram negative Enterobacteriaceae 42 (23.9%) including
Klebsiella pneumoniae 23 (13.1%), Escherichia coli 7
(3.9%), Proteus mirabilis 5 (2.8%), Enterobacter
aerogenes 3 (1.7%), Citrobacter freundii 3 (1.7%) and
Serratia marcescens 1 (0.6%). Other bacteria isolated
were Staphylococcus aureus 39 (22.2%) and
Acinetobacter baumannii 8 (4.5%) [Table 2].
Table 3 illustrates the antimicrobial resistance profiles of
the bacterial isolates. The most predominant bacterial
isolate Pseudomonas aeruginosa was resistant to
commonly used antipseudomonals i.e., ceftazidime
(72.4%), cefoperazone (70.1%), gentamicin (67.8%),
ciprofloxacin (60.9%), carbenicillin (58.6%), tobramycin
(56.3%), piperacillin (52.9%), amikacin (49.4%) and
cefoperazone/sulbactam (27.6%). P. aeruginosa was
least resistant to piperacillin/tazobactam 12.6% followed
by imipenem 9.2%. It is worth to note that 23 (59%) of

4. Dash et al. 462
Staphylococcus aureus were methicillin resistant.
However, these isolates were 100% susceptible to
vancomycin and linezolid.
DISCUSSION
Burns become infected because of thermal destruction of
the skin barrier and concomitant depression of local and
systemic host cellular and humoral immune responses
(Alexander, 1990). The burn wound surface is a protein-rich
environment consisting of avascular necrotic tissue
that provides a favorable niche for microbial colonization
and proliferation. Despite significant improvement in the
survival of burn patients, infectious complication
continues to be the major cause of morbidity and
mortality. The goal of burn wound management is to
reduce the onset and density of bacterial contamination
through early microbiological diagnosis, strict isolation
technique and proper implementation of infection control
policies (Amin and Kalantar, 2004).
In our study, female : male ratio of total burn patients was
1.17:1, similar to that of other studies conducted by
Akhter et al. and Batra et al. in India (Akther et al., 2010
and Batra 2003). In comparison, studies done by Ekrami
et al. in Iran and Bagdonas et al. in Lithuania showed
higher incidence of burn injuries among males (Ekrami
and Kalantar, 2007 and Bagdonas et al., 2004). In India
higher incidence of burn injuries among females may be
related to inadequate precautions during cooking,
wearing of loose Indian saries, inability to cope with the
physical and psychological stress of marriage and
harassment from parents-in-law (Bilwani and Gupta,
2003). The mean age of burn patients admitted to
hospital was 26.68 years, similar to that of other studies
(Akther et al., 2010, Ekrami and Kalantar, 2007 and
Bagdonas et al., 2004). High incidence among young
adults may be explained by the fact that they are
generally active and are exposed to hazardous situations
both in home and at work.
In this present study, high culture positivity of 88.6% was
found in the samples collected from burn patients. This is
in agreement with other studies (Ekrami and Kalantar,
2007 and Bagdonas et al., 2004). Our finding showed
that P. aeruginosa (49.4%) was the most common isolate
which coincides with many previous studies within and
outside India (Nagoba et al., 1999, Rajput et al., 2008
and Ekrami and Kalantar, 2007). However, study
conducted by Bagdonas et al. had revealed that S.
aureus (52.1%) was the most predominant isolate
(Bagdonas et al., 2004). Although S. aureus remains a
common cause of early burn wound infection, P.
aeruginosa from patient’s endogenous gastrointestinal
flora or moist environmental source is the most common
cause of burn wound infections. The second most
common isolate in our study was S. aureus (22.2%)
followed by K. pneumoniae (13.1%) and A. baumannii,
which is similar to other studies (Nagoba et al., 1999,
Rajput et al., 2008 and Ekrami and Kalantar, 2007).
Our study showed P. aeruginosa was highly resistant to
commonly used antipseudomonals and was least
resistant to piperacillin/tazobactam (12.6%) and
imipenem (9.2%). Similar finding of least resistant
antimicrobial imipenem against P. aeruginosa was
reported by Rajput et al. in Lucknow, India (Rajput et al.,
2008). Other Gram-negative bacilli were highly resistant
to commonly used ampicillin (92.9%), co-trimoxazole
(69%), ciprofloxacin (64.3%) and gentamicin (54.8%).
Similarly, piperacillin/tazobactam (90.5%) and imipenem
(100%) were found to be most effective antimicrobial
agents against Gram-negative bacilli. Multidrug resistant
Gram-negative bacilli that possesses several types of
beta-lactamases including extended spectrum beta-lactamases,
ampC beta-lactamases, and metallo beta-lactamases,
have been emerging as serious pathogens
in hospitalized patients (Clark et al., 2003). Low resistant
pattern shown by imipenem and piperacillin/tazobactam
may be due to its restricted use because of higher cost
and limited availability.
In our study, 59 percent of S. aureus were methicillin
resistant (MRSA). This result is in agreement with studies
done by Ekrami et al. and Rajput et al. where they had
found out 58% and 40% of MRSA isolates respectively.
(Rajput et al., 2008 and Ekrami and Kalantar, 2007).
These MRSA isolates showed 100% susceptibility to both
vancomycin and linezolid.
The high percentage of multidrug resistant isolates is
probably due to empirical use of broad-spectrum
antimicrobials prior to development of infection, extended
duration or previous hospitalization and non-adherence to
hospital antimicrobial policy. Strict infection control
practices i.e., physical isolation in a private room, use of
gowns and gloves during patient contact, hand washing
before and after each patient visit and appropriate
antimicrobial therapy are essential tools to reduce the
incidence of infections due to these multidrug resistant
organisms (Elliot and Lambert, 1999). Therefore, routine
institutional laboratory surveillance system involving
periodic sampling of burn wounds would facilitate the
selection and administration of appropriate empirical
systemic antimicrobial agents prior to the availability of
microbiological culture and susceptibility test results.
CONCLUSION
To conclude, burn patients were most commonly infected
with P. aeruginosa and S. aureus. Majority of these

5. isolates were multidrug resistant. In Gram-negative
isolates, imipenem or piperacillin/tazobactam and in
Gram-positive, vancomycin or linezolid can be used as
empirical antimicrobial therapy prior to the availability of
microbiological culture and susceptibility test results. A
burn unit-specific nosocomial infection surveillance
system may be introduced to reduce the incidence of
multidrug resistant infections among burn patients, and
for selecting appropriate antimicrobial agents.
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